Nowadays, a reliable clock generator is essential for every digital circuit to achieve precise timing of events. Such a clock generator is usually implemented by a phase-locked loop (PLL) in highly integrated circuits. For high speed data transmission application, the required clock frequency becomes higher than ever. However, high frequency signal suffers from serious electromagnetic interference (EMI). The electric field strength substantially increases at a center frequency, and this phenomenon may interrupt, obstruct, or degrade the performance of the circuit itself and other circuits. In addition, unpredictable impacts on human health may occur.
Therefore, to solve the aforementioned electromagnetic interference problems, a new clock generator which generates clock signals with reducing electromagnetic interference is needed.